Utilizes assertIn - tests/api/contrib

Using assertTrue and the 'in' operator to test
if an element is in a sequence is too python2.4.
Our unit testing framework supports assertIn,
which was created for these types of tests.
Adapting assertIn will enhance the readability of the test scripts.

Change-Id: Id2237b7a35c5c759e571b138faa8d1bef46a7e27
Merge "Utilizes assertIn - tests/api/contrib"